Jeffrey E Christian

Thermal evaluation of several configurations of insulation and structural materials for some metal stud walls

A series of two- and three-dimensional computer simulations was conducted for several metal stud walls. The Heating 7.2 finite difference computer code, developed at Oak Ridge National Laboratory, was used to model walls and their components. Maps of the temperature distribution in walls, their components, and the areas where walls intersect with other building structures were developed. These maps were used as an aid to estimate the areas of zones affected by existing thermal bridges and to calculate R-values for these areas. These R-values were used to calculate average R-values for whole walls and estimate the thermal effects of wall details. Using simulated R-values, several configurations of wall insulation were examined.

Thermal behavior of mixtures of perlite and phase change material in a simulated climate

Carefully controlled and well documented experiments have been done for two candidate configurations to control the heat load on a conditioned space. The 2:1 PCM/perlite mixture and the 6:1 PCM/perlite mixture, both on a weight basis, accomplished thermal control. The 2:1 system seemed to have enough PCM to be effective and involve a much larger fraction of its PCM in diurnal freezing and melting than the 6:1 system. It is a good starting point for engineering design of an optimum thermal control system. The results from the 2:1 system were reproduced with the computer program HEATING to prove that we know the relevant mechanisms and thermophysical properties of the PCM used in the system. Even without a model for the supersaturation and hysteresis that this material exhibited, HEATING reproduced the heat fluxes to the conditioned space in the experiments accurately enough to mirror the good thermal control performance of the system. The modified sensible heat capacity that was used in HEATING is a handy way to account for phase change effects and could be used in a subroutine to compute hourly phase change effects for whole building models like DOE-2. The experiments were done with PCM/perlite mixtures sealed in small methylmethacrylate boxes and covered top and bottom by XPS. The boxes allowed precise placement of the instrumentation used to follow the phase change effects. The XPS gave high R-value per unit thickness. A more practical prototype configuration such as PCM/perlite hermetically sealed in plastic pouches between layers of batts or blown-in insulation should be tested over a larger cross section. A good candidate is the whole attic cavity of the manufactured home test section used in the present work. Use of a PCM that does not exhibit supersaturation and hysteresis would make interpretation of the results easier. If the results of the larger scale test areas are as encouraging as the test cell results, a whole house model with a phase change algorithm should be constructed to optimize the configuration for the climate in which it will perform.

The Most Needed Building Foundations Research Products

This paper describes a research program targeted towards the significant potential for energy savings from improved residential building foundations design. A recent study at the University of Minnesota estimates that less than 5% of foundations in the present building stock are optimally insulated. In addition, this study indicates that the potential national savings from upgraded basements, crawl spaces, and slab-on-grade foundation systems in residential and small commercial buildings is about 0.5 quads/year (0.523 X 10 1 8 J/year). This research program is based upon a research needs assessment developed by the Building Foundations Research Review Panel. This panel was established by the U.S. Department of Energy (DOE) and Oak Ridge National Laboratory to assist in the formulation of DOE foundations research policy and the development of a technology transfer strategy to get this research to the marketplace. Half of the panel members are from private industry. One of the first tasks the panel addressed was to formulate a prioritized list of building foundation research needs. Building foundations research needs include: widescale dissemination of existing information on good practices for energy-efficient construction and retrofit, accurate characterization of the thermal properties of soils, validated foundation heat and mass transfer algorithms coupled into whole-building simulation models, an experimental data base from one or more well-characterized test sites, and design tools to effectively transfer the results of research into practice.

DOE Building America Technology and Energy Savings Analysis of Two 2721 ft2 Homes in a Mixed Humid Climate

The ZEBRAlliance is an opportunity to accelerate progress toward DOE s goal of maximizing cost-effective energy efficiency by investing in a highly leveraged, focused effort to test new ultra-high-efficiency components emerging from ORNL s Cooperative Research and Development Agreement (CRADA) partners and others. The Alliance integrated efficient components into the construction of four research houses that will be used as test markets to gauge the integral success of the components and houses. These four research houses are expected to be the first houses used to field-test several newly emerging products such as the ClimateMaster ground-source integrated heat pump, factory assembled ZEHcor walls, and one or more new appliances from Whirlpool Corporation.

Campbell Creek TVA 2010 First Year Performance Report July 1, 2009 August 31, 2010

This research project was initiated by TVA in March 2008 and encompasses three houses that are of similar size, design and located within the same community - Campbell Creek, Farragut TN with simulated occupancy. This report covers the performance period from July 1, 2009 to August 31, 2010. It is the intent of TVA that this Valley Data will inform electric utilities future residential retrofit incentive program.

Metal stud wall systems: Thermal disaster, or modern wall systems with highly efficient thermal insulation?

Metal stud wall systems for residential building are gaining in popularity. Thanks to their low cost, construction simplicity, and similarity to the existing wood frame technology, metal stud wall systems can share a considerable part of the residential and commercial markets, very soon. The prognosis of American Iron and Steel Institute predicts that in 1997 about 25% of the new residential buildings will be assembled with the use of metal studs technologies in the U.S.A. The application of the light gage metal technologies in building has either economical or environmental aspects, because the replacement of the construction lumber by metal wall and roof components can reduce construction costs but also save a forest. In addition, metal studs are 100% recyclable material. The authors believe that tremendous markets are available around the world for the deployment of the metal stud wall technologies. A deployment of the metal stud wall technologies can create a great chance for modern, low-cost and energy efficient buildings in many world regions. This system has been already successfully introduced in Europe, Central and South America, Australia and New Zealand. However, these technologies require serious redesign to improve their thermal performances. Commonly, commercially available metal stud wall systems are initially designed by simple replacement of wood studs, joists, headers, etc., by structurally equivalent metal components. Metal substitutes of the wood structure are very often being installed without consideration of the difference in thermal conductivity between wood and metal. Strong thermal bridges caused by highly conductive metal components worsen thermal performance of these walls. In metal stud walls, the reduction of the in-cavity R-value can reach 50%. Because steel has higher thermal conductivity than wood and intense heat transfer occurs through the metal wall components, thermal performances of a metal stud wall are significantly lower than for similar wood stud walls. A reduction of the in-cavity R-value caused by the wood studs is about 10% in wood stud walls. That is why metal stud walls are believed to be considerably less thermally effective than similar made of wood. However, properly designed metal stud walls can be as thermally effective as wood stud walls. Relatively high R-values may be achieved by installing insulating sheathing, which is widely used as a remedy for a weak thermal performance of metal stud walls. A series of the promising metal stud wall configurations is analyzed using results of finite difference computer modeling and guarded hotbox tests. Some of these walls were designed and tested in the ORNL Building Technology Center, some were tested in other laboratories, and some walls were developed and forgotten long time ago. Also, a novel concept of combined foam -metal studs is considered. The main aim of the present paper is to proof that it is possible to build metal stud walls performing as well as wood stud walls. The key lies in designing; metal stud wall systems have to be treated in special way with particular consideration to the high thermal conduction of metal components. In the discussed collection of the efficient metal stud wall configurations, reductions of the in-cavity R-value caused by metal studs are between 10 and 20%.